Examples

These medications are given in eyedrop form. The most commonly used adrenergic agonist (brimonidine tartrate) eyedrops have a purple bottle cap. If you need to use more than one type of eyedrop, you may need to take each medication in a certain order. You can use the color of the bottle cap to help you remember when to use each type of eyedrop.

If you are using more than one type of eyedrop, wait 5 minutes between the different eyedrop medicines.

How It Works

Most adrenergic agonists reduce the pressure in the eyes by reducing how much fluid (aqueous humor) the eyes produce. They also increase the amount of fluid that drains out of the eyes.

Why It Is Used

These medications may be used along with other medications to treat glaucoma.

Apraclonidine and brimonidine are used to treat high pressure in the eyes in people with open-angle glaucoma. They are also used to prevent high pressure in an eye after laser treatment for glaucoma. For everyday use, brimonidine (Alphagan) is replacing apraclonidine (Iopidine) because it is less likely to cause an allergic reaction. Some pharmacies no longer carry apraclonidine eyedrops.

Dipivefrin is converted to epinephrine in the body. Because newer adrenergic agonists are more effective and have fewer side effects, dipivefrin is used only rarely.

Epinephrine is rarely used since apraclonidine and brimonidine are just as effective with fewer side effects.

How Well It Works

These medications reduce the pressure in the eyes. Reducing the pressure in the eyes reduces the chances of damage to the optic nerve, preventing further vision loss.

Side Effects

Side effects of adrenergic agonists include:

• Redness and stinging in the eyes.
• Allergic reaction in the eyes (itching).
• Dry mouth (very common with the newer medications but usually improves over time).
• Drowsiness, nervousness, and headaches.
• Fast or irregular heartbeat.
• Increased blood pressure.

Adrenergic agonists (especially epinephrine) may widen (dilate) the pupil. This may trigger closed-angle glaucoma in people who have narrow drainage angles.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Brimonidine should not be used if a person is taking a monoamine oxidase inhibitor (MAOI), used to treat depression. People who are taking tricyclic antidepressants and those with severe heart, liver, or kidney disease may not be able to take this medication.

Epinephrine drops tighten (constrict) the blood vessels on the eye's surface, taking the red out of the white part of the eye. After 2 to 3 hours, the vessels open (dilate) and the eye becomes red again. People may be tempted to overuse this medication to keep the red out of their eyes.

Apraclonidine and, less commonly, brimonidine may cause allergy problems in some people when used over a long period of time.

These medications need to be used with caution in older adults and people who have high blood pressure, diabetes, an overactive thyroid gland (hyperthyroidism), or heart disease.

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